a GUI for nix package manager


* nixgui
  Provide a simple graphical user interface for installing and 

* Hacking on nixgui
** wx events and reactive banana
   If you want to get a double click event from a widget, then you
   should always use =Reactive.Banana.WX.Extra.doubleClickEvent=.
   This is because the =doubleClick= event from =wxHaskell= is
   write-only.  Your Program will crash on double click if you
   directly call =event1 (doubleClick widget)=.